suckerfish vs sucking fish

suckerfish and sucking fish both are nouns.

Word	Noun	Adjective	Verb	Adverb
suckerfish	Yes	No	No	No
sucking fish	Yes	No	No	No

As nouns, suckerfish and sucking fish are synonyms defined as:

suckerfish and sucking fish: marine fishes with a flattened elongated body and a sucking disk on the head for attaching to large fish or moving objects

Other synonyms of suckerfish include remora.

suckerfish (noun)	sucking fish (noun)
marine fishes with a flattened elongated body and a sucking disk on the head for attaching to large fish or moving objects	marine fishes with a flattened elongated body and a sucking disk on the head for attaching to large fish or moving objects